Conventionally desks in the market are substantially standardized for the convenience of both manufacturers and users. Although the desks are standardized, a plurality of different standards exist or the standard varies in countries. This becomes an obstacle to unification of a manufacturing line of the desks. In addition to this situation, office machines placed on a top plate of a desk have remarkably been increased due to a rapid progress of office automation. A top plates has generally been rectangular, however, top plates having a variety of shapes come into appearance recently so as to cooperate with recent office automation. Further, an odd-shaped top plate to connect top plates of adjoining desks may be required to improve mobility of an office or to fulfill environment of an office. As described above, a specification of a desk to be manufactured is expected to become more and more diversified in the future.
In a frame which supports a top plate, a suitable position at which the top plate is supported differs according to a specification of the top plate. For an optional component such as a shelf, an electrical outlet or a telephone stand, a position on which the component is mounted or an arrangement of mounting the component varies in accordance with a specification of the top plate. In view of the above situation, the frame supporting the top plate has been designed and manufactured one by one to satisfy a demand. However, in the above-described top plate, if the frame is manufactured as conventionally, productivity is getting worse and worse and handling in packing or distribution is getting troublesome.